330 C. E. MCCLUNG. 



hopper this pairwise union of chromosomes continues in exist- 

 ence through fully half the life of the individual. If the chromo- 

 somes are centers of specific energies it is at this time that they 

 would best be able to influence each other. Montgomery regards 

 this as a phenomenon parallel to what occurs in the conjugation 

 of the lower organisms, and so considers it a process of rejuve- 

 nation. This is a very loose term, and according to Montgom- 

 ery's conception seems to mean nothing more than a stimulus to 

 growth, for it is his conclusion that because of the conjugation 

 of the chromosomes the germ cells immediately proceed to in- 

 crease in size and attain dimensions in excess of those reached at 

 any other period of their existence. 



To me there is a much deeper meaning in this intimate and 

 long continued association of the chromosomes which, as I have 

 recorded for Chortophaga, may be established in the early sperma- 

 togonia. If there is to be a balancing of forces between homol- 

 ogous chromosomes this would seem to be the place where it 

 must occur. We find, as a matter of fact, that in normal breed- 

 ings there are produced germ cells that are either entirely pure 

 in regard to certain characters or that develop intermediate results 

 between the two extremes of the parents. The same individuals 

 may show the alternative inheritance of one character and the 

 blended inheritance of another. These phenomena would seem 

 susceptible of a reasonable explanation if we should consider that 

 in the first instance the interaction between the homologous 

 chromosomes was slight, or entirely lacking, while in the second 

 case it was more extensive. Upon the occurrence of the reduc- 

 ing division the linked chromosomes of the first example would 

 separate practically unchanged, while in the other they would 

 pass into the germ cells with different potentialities than they 

 possessed before their synapsis. 



If parents of different species were employed we might expect 

 the same results and secure second generations of inbred hybrids 

 that would show pure parental characters or various blends of 

 these. Mosaics might easily be accounted for if we assume that 

 the exchange between the chromosomes has been of such a 

 character as to produce nearly a balance of the alternative char- 

 acters. Through inequalities of division or by reason of different 



